JP2009524465A - Dental instruments - Google Patents

Abstract

To prevent clogging of a cutting edge of a file along a spiral groove of a file for endodontic treatment.
An apparatus for use in cleaning the root canal using an endodontic file (10) is disclosed. The file is mounted on a drill head (16) driven by an electric motor (22). The electric motor (22) is normally driven in one forward direction, but periodically rotates the electric motor (22) at normal speed or at a speed and / or direction significantly different from the normal direction for a very short time. Let Due to the inertia and looseness of the transmission between the motor output shaft (40) and the drill head (16), the direction of rotation of the file in the root canal does not change.
[Selection] Figure 3

Description

  The present invention relates to a root canal operation, and in particular to an instrument for forming and cleaning a root canal in preparation for filling the root canal.

  Endodontics is the name given to root canal treatment. Endodontic treatment is the conventional removal of irreparably damaged nerve tissue or pulp and dentin, followed by cleaning and disinfection of the root canal space, and subsequent prevention of future bacterial infections. Occlusion or filling of the root canal to form a possible seal.

  The root canal is formed and cleaned using an endodontic file mounted on a power drill or manually operated. The file is moved in and out of the root canal, and when manually operated, it can be rotated in both directions to wind a clock, or it can be rotated continuously in one direction as well. Is possible.

  An endodontic file is a very thin probe with an actuating part that has a helical groove that tapers towards one apex, and also directs the file itself along a root canal that is not perfectly straight. It is possible to have at least some flexibility. Endodontic files are either electric or manual. The electric file (which is here related) includes a mandrel portion that is attached to and engaged with the drill head so that the file can be driven to rotate. As used herein, reference is made to a method of rotating an endodontic file within a root canal, as well as forming and filling.

  However, the endodontic file becomes clogged with debris that cannot always be removed from the cutting edge of the file along the helical groove of the file, and the present invention seeks to solve this problem. This can cause a reduction in cutting efficiency and, in severe cases, can cause files to break in the teeth.

  According to the present invention, a device for forming and cleaning a root canal is proposed, which device is for mounting a drill driven by an electric motor via a transmission system, an endodontic file on the drill head. And means for intermittently causing the motor to rotate at a normal speed in the normal rotation direction and to rotate the motor at a normal speed or a speed and / or direction significantly different from the normal direction for a very short time. Is proposed.

  The speed significantly different from the normal speed is preferably the speed in the opposite rotational direction, that is, the motor is rotated intermittently in the opposite direction to the normal speed direction.

  In a conventional dental drill with an electric motor for rotating the drill chuck, there is some play in the drive train between the motor itself and the drill head, i.e. the gear of the dental handpiece. This play can be the result of loosening in the gear train, or other types of play, or the result of energy absorption between the motor and the endodontic file. Drive trains and motors will also have inertia to consider.

  The endodontic file includes a plurality of grooves, at least some of which are in frictional contact with the root canal wall when the file is driven. The portion of the file between the portion in contact with the root canal wall and the portion attached to the drill head is loaded by twisting and thus stores energy in the form of torsional energy. When this twisting is performed, the file is “winded up” and, as a result of the “winding up” of the file, the portion of the file between the portion that is in frictional contact with the root canal wall and the portion that is attached to the drill head Expands radially.

  By reversing the direction of the motor and then restoring to the original direction of rotation, a pulse is generated in the transmission between the motor and the drill head. The pulse breaks the connection between the motor and the drill groove, so that the energy stored in the file is released by pre-twisting the groove, driving the groove.

  When the torsional energy is released, the groove is released and the diameter decreases. Depending on the position along the length of the file where the file is in frictional contact with the root canal wall, the portion of the released file may momentarily rotate in either direction.

  It is preferable to reverse the direction of the current for driving the motor to temporarily stop the normal speed of the motor. By reversing the direction of the current for a short time, the motor may or may not actually rotate in the opposite direction, but causes a pause in the normal speed of the motor.

  Transmission pulses are also obtained by intermittently decelerating or accelerating the motor at a frequency that ensures a change in rotational speed but does not change the direction of rotation of the motor. This may include decelerating until the motor stops and accelerating until the motor returns to its normal operating speed.

  Although a random program of changes is also effective, it is preferred that the intermittent changes in motor rotation be performed regularly.

  The normal speed can usually range from 300 rpm to 650 rpm.

  The extremely short time during which the normal speed is paused is, for example, in the range of 1 to 4 milliseconds, and this pause is carried out at a frequency of, for example, up to 100 Hz. However, the frequency is very dependent on the rotational speed. A prerequisite is that the drive train gears are held in mesh, which requires the same degree of rotation, regardless of speed. Thus, the speed will affect the rate at which “unwinding” is obtained. When the forward rotational speed is higher, the duration of the reverse pulse needs to be shorter than when the speed is low, or the reverse pulse is different from the speed in the forward direction and drives the motor back at a lower speed May have a size intended for that. In the latter case, the extremely short time during which the normal speed is paused is a maximum of 10 milliseconds.

  In particular, in the case of a file that rotates faster (up to 2000 rpm), a reverse current may be necessary to obtain sufficient deceleration, but in order to obtain the effects of the present invention, the rotational speed must be greatly reduced. Only is needed.

  The motor is preferably a stepping motor whose speed and / or direction can be easily changed, but in the present invention also the frequency and range of intermittent pauses of normal speed are particularly within the motor drive circuit. When it can be set and programmed, a continuous rotary motor can be used.

  The present invention also relates to a method for forming and cleaning a root canal using a dental drill driven by an electric motor, wherein the endodontic file is mounted on a drill head and the motor has a groove in the cutting mode. When operating at normal speed in the normal direction of rotation and when the file is in the root canal, the motor is driven intermittently for a very short time at normal speed or at a speed and / or direction significantly different from the normal direction. It is related with the method characterized by this.

  The speed significantly different from the normal speed is preferably the speed in the opposite rotational direction, that is, the motor rotates intermittently in the reverse direction with respect to the normal speed direction.

  The present invention is not limited to root canal dental work (which may be used for post space preparation), or is not limited to general dental work. . The method of the present invention applies to any work where it is desired to pulse or vibrate the rotating bit when it is working without stopping the rotation and cutting, such as a drill or file. Can do.

  It is widely accepted that the majority of rotary endodontic file loading is related to the cutting process, i.e., dentin debris caused by both the friction and processing / extraction elements.

  In order to evaluate the cutting efficiency, it is possible to measure the clockwise (cutting) rotation speed achieved to reach the desired cutting depth in a sample of the test material, this technology is the optimal parameter for motor rotation Can be used to evaluate The realized clockwise (cutting) rotational speed can be used as a means for evaluating the discharge efficiency of the fragments.

  The invention will become more apparent from the following description, given by way of example with reference to the accompanying drawings.

  FIG. 1 illustrates an enlarged view of the endodontic file in a relaxed state.

  FIG. 2 illustrates the file of FIG. 1 after the file has been “rolled up” and inserted into the root canal.

  FIG. 3 is a schematic view of a dental handpiece with an electric motor and a drive train between the motor and the drill head.

  FIG. 4 is a cross-sectional view of a dental handpiece connected to an electric motor.

  FIG. 5 is a schematic diagram of a control circuit used to implement the present invention.

  The endodontic file 10 shown in FIG. 1 includes a mandrel 12 formed to fit within the drill head of a drill handpiece and an actuating portion 14 with a tapered helical groove. The file is configured to rotate in one direction, and the groove comprises a leading edge that cuts or scrapes the dentin from the root canal wall. As the file rotates, they cut the dentin from the tooth wall and collect the remaining soft pulp tissue.

  The file is made of a flexible alloy and can therefore bend while rotating and follow the curvature of the root canal, thereby following a tortuous path. Also, the flexibility of the alloy means that when the file is "rolled up", that is, when torque is applied to the head of the file and a portion of the file is in frictional contact with the root canal wall, the file twists. . As a result of the winding of the file, the file portion between the friction contact portion with the root canal wall and the mandrel 12 expands in the radial direction.

  When the file is rolled up, the blade is released. The file has a larger diameter and a longer length. This can be seen in FIG. 2 where the file is illustrated in the root canal of the tooth 15. The increase in diameter causes the blade to remain engaged with the dentin wall, creating a file action on the long axis of the root canal (in addition to the file action produced by the axial vector of rotation). As the file is rolled up, the spacing between the grooves also increases.

  When the file is unwound, the blade is rolled up, away from the root canal wall, and additionally moved axially, reducing the spacing between the grooves, thereby moving the dentin slices and the blade into the root canal. Since it is away from the wall, the section is not carried in the distal direction (i.e., not towards the bottom of the root canal). This is the “pumping” of the dentin slice. It creates another mechanism for debris removal.

  The file mechanism of the endodontic file is related to the rake angle (the angle formed by the leading edge of the groove with respect to the root canal wall) and other parameters such as rotational speed, drive torque, and advance force. A positive rake angle provides better pumping and restores the cutting attitude of the loose groove without moving the section in the distal direction, which acts as a non-return valve. Files with the trade names of Hero Shaper, GT and Pro-Taper would be particularly suitable.

  The mechanism is also proportional to the diameter of the file, and the larger the file diameter, the less likely it will need to improve as a fine file.

  The present invention is applied to a file configured to rotate continuously. The file shown in the drawings has a tapered shape, but the techniques described herein are equally applicable to files of other shapes.

  FIG. 3 shows an arrangement for driving the endodontic file 10. The file is mounted in the head 16 of the dental handpiece 18. The handpiece is connected to the housing 20, and the motor 22 is built in the housing. When the handpiece is connected to the housing 20, the motor drives the file 10 to rotate.

  The motor is controlled from a remote control device 24. The control device is set to drive a motor (preferably a stepping motor) in the forward direction and periodically reverse the rotation direction of the motor. The motor will run backwards for a very short time (if any) before the current returns in the forward direction (for example, the reverse current can be applied for 2 milliseconds) and the play of the transmission from the motor to the file is This means that the file does not actually rotate in the opposite direction. When the rotation of the motor changes from the forward rotation to the reverse rotation, the rotation of the motor is reversed and may momentarily become zero rpm, but the rotation of the motor never stops. . However, the forward movement of the file decelerates, at which time it accelerates and causes a pulse in the file.

  FIG. 4 shows a transmission path of a conventional drill handpiece, through which the motor 22 rotates the drill head 16. The motor includes an output shaft 40 that is splined to the motor rotor at point 42. The outer end of the shaft 40 includes a turner 44 that is pushed into a spring-loaded socket 46 that, on the opposite side, meshes with a first drive shaft portion 48. This first drive shaft portion connects with the second drive shaft portion 50 within the universal joint 52. The second drive shaft portion 50 has an end in the bevel gear 54, and the bevel gear 54 is engaged so as to rotate about an axis perpendicular to the direction of rotation of the second drive shaft portion 50. It meshes with the bevel gear 56. The bevel gear 56 is fast with a drive plate 58 that meshes with the dental drill or, in this case, the non-rounded part on the mandrel of the endodontic file.

  There is some play or slack between each of these components of this drive train, and overall this prevents the drive plate 58 from reversing itself during short periods of reverse motor rotation. Has been.

  A pulse may be an instantaneous change in torque applied to a file mandrel. Therefore, it is considered that the file is lightly released when the torque is reduced, and is wound up when a higher torque is applied again. As the total amount of torsional energy stored in the file changes, the physical dimensions of the groove change. The change in the physical dimension of the groove may occur partially in the filed groove part rotating in the opposite direction, so that the back edge of the groove may become the leading edge for a short period of time.

  FIG. 5 shows details of the motor control device 24. The operator control module 26 allows the operator to set the pulse width (ie motor reverse rotation period) and speed (ie motor reverse rotation frequency), and the display 28 displays the motor rpm, rotation direction, voltage and current. indicate. The current and voltage can be used as a metric for the work that the file is performing for a specified depth of cut in the root canal. Module 26 feeds to microprocessor 30, which generates a pulse train with a pulse width modulated at a selected frequency. The microprocessor also measures the motor current and voltage.

  The motor controller 32 provides output switching of motor supply, current limit and direction control, and the encoder 34 feeds back the rotation data of the processor 28.

  The power supply 36 supplies power to all the processor functions and supplies a DC supply to the motor 22.

  The required reverse pulse magnitude and / or frequency appears to be inversely proportional to the diameter of the file and appears to be proportional to the speed at which the file is driven.

  Increasing the frequency of the pulse shortens the time allowed to slow down the file sufficiently to have an appropriate effect on the speed of the file in the root canal.

  The greater the flexibility of the file, the longer the pulse.

  As a result of the improved efficiency that can be exploited as an effect of the present invention, files made from various alloys or even from composite materials can be used. For example, stainless steel can be used at a very low rpm.

  The test showed good results when the motor was driven in the reverse direction for a very short period of time. By applying instantaneous forward acceleration and deceleration pulses, the same effect will very well occur. This would be very convenient for rigid drill bits.

  This is also applicable to rapid reverse or forward “washing” or “filed” applications, or indeed possible applications of vibrations with a particular waveform.

  The frequency of reverse rotation of the motor varies in proportion to the depth of insertion of the endodontic file in the root canal. Because the file shape is tapered, as the file enters the root canal, the diameter of the portion of the file within the root canal increases, and the pulse is required to have a shorter duration or increase in frequency.

  It is possible to electronically monitor the rate of advancement of the tip, and feedback from this monitor can be used to adjust the duration and / or frequency of the motor pause to obtain the optimal progress.

The enlarged view of the file for endodontic treatment of the loose state. The figure which shows the file of FIG. 1 after "rolling up" the file and fitting it in the root canal. 1 is a schematic view of an electric motor and a dental handpiece including a drive train between the motor and a drill head. Sectional view of a dental handpiece connected to an electric motor. 1 is a schematic diagram of a control circuit used to implement the present invention.

Explanation of symbols

12 Mandrel 10 Endodontic File 15 Teeth 16 Drill Head 18 Dental Handpiece 20 Housing 22 Motor 24 Motor Controller 26 Operator Control Module 34 Encoder 36 Power Supply 40 Output Shaft 44 Turn 46 46 Socket 50 Second Drive Shaft Part 52 Universal joint 54, 56 Bevel gear

Claims (19)

  A device for forming and cleaning a root canal, which is driven by an electric motor via a transmission, a plurality of means for mounting endodontic files on the drill head, and the motor in the normal direction at normal speed A device comprising a plurality of means for rotating and intermittently rotating the motor at a speed and / or direction significantly different from normal speed or normal direction for a very short time.   The device according to claim 1, wherein the speed significantly different from the normal speed is a speed in the opposite direction of rotation.   The apparatus according to claim 1, wherein the motor is a stepping motor.   The device according to claim 1, wherein the transmission device comprises a drive shaft and meshing gears and / or a rotating gear.   5. A device according to any one of claims 2 to 4, characterized in that the time for the motor to reverse is shorter than the time required to produce the reverse rotation of the endodontic file.   6. An apparatus according to any one of the preceding claims, characterized in that intermittent changes in motor rotation are preferably made regularly.   7. A device according to any one of the preceding claims, characterized in that the normal speed is in the range of 300 rpm to 650 rpm.   8. A device according to any one of the preceding claims, characterized in that the very short time during which the normal speed is paused is in the range of 1-4 milliseconds.   The apparatus according to claim 1, wherein the pause is performed at a frequency of 100 Hz or less.   A method of forming and cleaning a root canal using a dental drill driven by an electric motor, wherein the endodontic file is mounted on the drill head and the motor is normal in the normal direction of rotation with the file groove in cutting mode Acting at speed and when the file is in the root canal, the motor is intermittently driven for a very short time at a speed and / or direction significantly different from normal speed or normal direction Method.   The method according to claim 10, wherein the speed significantly different from the normal speed is a speed in the opposite direction of rotation.   12. A method according to claim 11, characterized in that the time for the motor to reverse is shorter than the time required to cause reverse rotation of the endodontic file.   13. A method according to any one of claims 10 to 12, characterized in that intermittent changes in motor rotation are preferably performed regularly.   The method according to claim 10, wherein the normal speed is in the range of 300 rpm to 650 rpm.   15. A method according to any one of claims 10 to 14, characterized in that the very short time that the normal speed is paused is in the range of 1-4 milliseconds.   The method according to claim 10, wherein the pause is performed at a frequency of 100 Hz or less.   A method of operating a rotating tool using a drill driven by an electric motor, wherein the rotating bit is mounted on the drill head, the motor is actuated in a first direction in which the bit rotates in the forward direction, and the bit When the gear is engaged with the workpiece, the motor is driven backwards for a very short time, thereby causing no change in the direction of rotation of the bit.   An apparatus mainly for forming and washing root canals as described with reference to the accompanying drawings.   A method mainly for forming and washing root canals as described with reference to the accompanying drawings.

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